Temperature-humidity synergistic effects on predominant intestinal infectious diseases in Shenzhen, China: A...

The prevalence of intestinal infectious diseases (IIDs) in densely populated cities substantially escalates the burden of disease. An ecological study on the epidemiological trends of predominant IIDs-hand, foot, and mouth disease (HFMD), viral diarrhea (DV), and non-viral diarrhea (DN)-was conducted in Shenzhen, China (2012-2022), aiming to elucidate the associations of meteorological factors, including extreme temperatures, seasonal variations, and temperature-humidity interactions with IID transmission, and to establish a monitoring and early warning framework. We assessed temperature-related morbidity's short-term lagged effects, long-term cumulative impacts, and seasonal patterns using distributed lag non-linear models, finding that high temperatures (30°C) significantly increase HFMD and DN risks, low temperatures (13.8°C) worsen DV infections, and high temperatures have specific pathogenic effects on individuals aged 0 and over 20 years. Humidity-mediated seasonal variations in the incidence of IIDs were identified within equivalent temperature ranges. Generalized additive models (GAMs) further decoded the incidence patterns of IIDs across population subgroups under temperature-humidity interactions. An early warning model based on temperature-humidity indicators successfully predicted HFMD and DV outbreaks, establishing a novel framework for future epidemiological analyses grounded in temperature-humidity evidence. This study provides actionable insights for optimizing region-specific public health interventions and strengthening early risk mitigation strategies.